Optically accessible microfluidic diagnostic device

Abstract

A microfluidic diagnostic device ( 1, 50 ) comprising a substrate ( 4 ); a compatible layer ( 6 ) formed on a first face ( 4 a ) of the substrate ( 4 ); a structural layer ( 8 ), formed on top of the compatible layer ( 6 ); a channel ( 10 ), formed in the structural layer ( 8 ) and limited underneath by the compatible layer ( 6 ), optically accessible by a first luminous radiation having a first wavelength (λ e ); and a cover layer ( 18 ) made of a material transparent to the first wavelength (λ e ), arranged on top of the structural layer ( 8 ) and sealing the channel ( 10 ) at the top, wherein the compatible layer ( 6 ) has a thickness equal to approximately a quarter of the first wavelength (λ e ) divided by the refraction index of the compatible layer ( 6 ), or equal to an odd multiple of a quarter of the first wavelength (λ e ) divided by the refraction index of the compatible layer ( 6 ).

What is claimed is: 
     
       1. A microfluidic diagnostic device comprising:
 a substrate; 
 a compatible layer formed on a upper face of the substrate and having a refraction index; 
 a structural layer, formed on top of the compatible layer; 
 a channel, formed in the structural layer and limited underneath by the compatible layer, said channel being optically accessible from above by a first luminous radiation having a first wavelength (λ e ); and 
 an inlet hole and an outlet hole each extending through the substrate and the compatible layer and in microfluidic connection with said channel, said inlet hole and said outlet hole formed starting from a bottom, external face of said microfluidic diagnostic device, opposite to an optically accessible top face,
 said compatible layer being substantially transparent to the first wavelength (λ e ) and having a thickness equal to approximately a quarter of the first wavelength (λ e ) divided by the refraction index of said compatible layer, or equal to an odd multiple of a quarter of the first wavelength (λ e ) divided by the refraction index of said compatible layer; and 
 the compatible layer being arranged in such a way that the incidence angle of the incident light radiation is approximately orthogonal to the surface of the compatible layer. 
 
 
     
     
       2. The device according to  claim 1 , wherein said substrate is made of silicon, and the compatible layer is made of silicon oxide. 
     
     
       3. The device according to  claim 1 , further comprising a cover layer made of a material transparent to the first wavelength (λ e ), arranged on top of the structural layer and sealing the channel at the top. 
     
     
       4. The device according to  claim 3 , wherein the cover layer is made of a polymeric material transparent to said first wavelength (λ e ). 
     
     
       5. The device according to  claim 2 , wherein the structural layer is made of photoresist. 
     
     
       6. The device according to  claim 1 , wherein said channel has a shape chosen in the group comprising rectangular, circular, polygonal, and polygonal with rounded corners, and extends in depth in the structural layer throughout the thickness of the structural layer. 
     
     
       7. The device according to  claim 1 , wherein said channel has a height of between 1 μm and 1000 μm. 
     
     
       8. The device according to  claim 1 , further comprising a supporting layer, formed on a second face, opposite to the first face, of the substrate and comprising a through hole arranged as a continuation of the inlet hole, said through hole being provided with a removable hermetic closing element. 
     
     
       9. The device according to  claim 1 , wherein said channel houses at least one detection region comprising probe molecules adapted to detect respective target molecules. 
     
     
       10. The device according to  claim 9 , wherein said probe molecules are grafted to the compatible layer inside the channel. 
     
     
       11. The device according to  claim 10 , wherein said probe molecules are labelled with marker molecules which, when activated and excited by said first luminous radiation, are adapted to emit a second luminous radiation having a second wavelength (λ f ), said compatible layer being transparent to said first and said second luminous radiation. 
     
     
       12. A diagnostic system comprising:
 a microfluidic diagnostic device according to  claim 3 ; 
 a generator of light radiation facing the cover layer and configured for generating excitation light radiation having the first wavelength (λ e ) towards said microfluidic diagnostic device; 
 a detector of light radiation facing the cover layer and configured for collecting a light radiation emitted by said microfluidic diagnostic device, said emitted light radiation having a second wavelength (λ f ) different from the first wavelength (λ e ); and 
 a processor, connected to the detector of light radiation and configured for acquiring an image of said emitted light radiation and identifying, from said image, an intensity of said emitted light radiation. 
 
     
     
       13. The system according to  claim 12 , comprising a fluorescence microscope including the generator of light radiation and the detector of light radiation.